(astronomy) The magnitude of a star as determined by radiometry.

Arranged like rays that radiate from, or converge to a common centre. / Moving along a radius. / (anatomy) Of, or relating to the radius bone.

A radial tire / radial tyre.

Motion of an object toward or away from an observer. / (astronomy) Motion of a star toward or away from the earth.

A radioactive isotope of carbon, especially ¹⁴₆C

(physics, archaeology, paleontology) A method of estimating the age of an artifact or biological vestige based on the relative amounts of the different isotopes of carbon present in a sample.

(mathematics) The line containing the locus of points from which the segments respectively tangent to two given circles have equal length.

a device that allows two-way communication via radio

To communicate via such a device

(chemistry) Any radical that also carries an electric charge; typically, the charge and unpaired electron are associated with the same atom.